1. Field of the Invention
The present invention relates to a technology of fine structure pattern transcription for transcribing a fine protrusion-depression pattern on a transcription object.
2. Description of Related Art
Fine pattering and integration of a semiconductor integrated circuit have been progressed in recent years. As a result, a patterning dimension of the circuit has been shrunk as small as a light source wave length which is used for a photolithography technology. Therefore, a conventional photolithography technology is reaching to a limit as a pattern formation technology. Then, for finer and more precise patterning, an electron beam lithography apparatus, which is a kind of a charged particle beam apparatus, is considered as a pattern formation technology instead of the photolithography technology.
However, a pattern formation method of the electron beam lithography apparatus is a direct drawing method of a mask pattern, which is different from a pattern formation method of a one-shot exposure method using a light source such as i-line and an excimer laser. Therefore, in the pattern formation method using the electron beam lithography apparatus, an exposure time (drawing time) increases according to a writing length of a pattern. Accordingly, a long time is required for completing the pattern.
Therefore, in proportion to a degree of integration of a semiconductor integrated circuit, a time required for the pattern formation increases, thereby resulting in reduction of a throughput. Then, for speeding up the electron beam lithography apparatus, a technology of one-shot drawing radiation method is considered, in which various shapes of masks are combined and the electron beam is irradiated with one-shot for diffusing a shape of the beam. However, since a degree of requirement for fine patterning has progressed, there are many factors which raise a fabrication cost, for example, growing in size of the electron beam apparatus and increase in mask alignment.
Under conditions described above, recently, an imprint technology has gotten a lot of attention as a technology for forming a fine pattern at low cost. The imprint technology prepares a stamper in advance which has a protrusion-depression pattern which is identical to a pattern to be formed on a surface of a substrate using, for example, a photolithography technology or an electron beam lithography apparatus. The technology has a simple procedure for transcribing a predetermined pattern, that is, the stamper is pressed on a resist film which is coated on a surface of a transcription substrate, then separated.
An electron beam lithography apparatus is required for fabricating a stamper. However, by using the stamper as a master, a plurality of replicas are fabricated. As a result, a total cost can be reduced by using the replicas for an actual pattern transcription. The imprint technology is being studied to apply to, for example, a formation of a memory bit of a large volume storage medium, as well as a pattern formation of a semiconductor integrated circuit.
In the imprint technology, a pressure of a stamper which is pressed on a surface of a pattern transcription region is required to be uniform for precisely transcribing a fine pattern on a transcription substrate such as a substrate for a semiconductor integrated circuit and a large volume storage medium.
For example, a transcription technology is disclosed in U.S. Pat. No. 6,696,220, in which a stamper is mechanically pressed on a part of a surface of a transcription substrate to form a fine pattern. However, since the surface of the transcription substrate has fine waves, it becomes difficult to make a surface of the stamper to follow the fine waves of the transcription substrate, especially, when the pattern transcription region becomes large.
As a technology for uniformly pressing a large transcription substrate which has the fine waves on its surface, for example, a technology is disclosed in Japanese Laid-Open Patent Publication No. 2003-157520, in which an applied pressure is uniformed by inserting a pressure buffer layer between a stamper or transcription substrate and a press head. In addition, in US Laid-Open Patent Publication No. 0189273 in 2003, a technology is disclosed, in which a room for encapsulating a fluid instead of the pressure buffer layer is disposed behind a stamper or transcription substrate. Further, in U.S. Pat. No. 6,482,742, a technology is disclosed, in which a stamper and a transcription substrate are arranged in a chamber whose pressure is adjustable, and a uniform pressure is applied to the stamper and the transcription substrate as a whole by encapsulating a fluid, for example, a gas in the chamber. As a result, a fine pattern can be formed on a wafer of up to 200 mm in diameter.
In the conventional technology, a control of in-plane stress distribution corresponding to a surface status and an outer shape of a stamper and a transcription substrate has been difficult.
As a method for solving the above issues, a method which gives an in-plane stress distribution is considered, in which a stage is disposed keeping a clearance at a position close to a surface of a stamper and a transcription substrate, and a fluid is blown out in the space from a predetermined position of the stage.
However, in the method described above, since a space which expands around the stamper and the transcription substrate is extremely large compared with a space between the transcription substrate and the stage, a stress distribution in the space which is obtained by blowing out a fluid in the narrow space rapidly decreases toward an end portion of the stamper and the transcription substrate.
This causes an insufficient pressure in the vicinity of the end portion of the stamper and the transcription substrate, thereby resulting in generation of a new problem such as a pattern transcription failure and a reduction of an effective transcription area.
Therefore, it is desirable to provide a fine structure pattern transcription method and a fine structure pattern transcription apparatus which can prevent a pressure, which is required for pressing a stamper on a surface of a transcription substrate, from dropping in an end portion of the stamper.